The present invention relates generally to permeable membrane sealing apparatus and, more particularly, to an aerator pad assembly for railway hopper cars.
Closed railway hopper cars with pneumatic systems for unloading are used for the transportation of powdered and granular products. For cars with positive pressure pneumatic systems, air may be supplied from an external source to pressurize the interior of the car body and simultaneously fluidize the dry, bulk product carried within the car to enable it to be conveyed in a fluidized state through product transfer conduits from the car to a collection facility. Air pressure within the hopper car during unloading is typically maintained at approximately fifteen pounds per square inch gauge pressure.
Aerator tub assemblies are often installed adjacent to a discharge opening for each hopper of a railway hopper car. The aerator tub assemblies sometimes incorporate aerator pad assemblies, including an aeration fabric and elastomeric gasket. Fasteners used to secure the aerator pad assembly generally require openings in the aerator pad assembly for proper installation. These openings often provide a path for air to escape from the pressurized hopper car. Consequently, the air pressure within the hopper car is often reduced and/or performance of the discharge system may be diminished.
In accordance with the teachings of the present invention, disadvantages and problems associated with fabrication, assembly and use of aerator pad assemblies have been substantially reduced or eliminated.
One embodiment of the present invention provides an aerator pad assembly having an aeration pad with a perimeter and a number of cutouts. The aeration pad may include a number of reinforcing supports providing additional strength and durability. A gasket may be disposed about the perimeter, the gasket having a plurality of protuberances with fastener openings disposed therethrough, and the protuberances preferably cooperate with the cutouts to form a continuous interface therebetween. In one embodiment, a notched opening within the gasket is provided at a generally continuous interface with the perimeter of the aerator pad at least partially occupying a portion of the notched opening.
In a particular embodiment, the gasket may be molded onto the aeration pad. In another embodiment, an adhesive material may be used to bond or attach the gasket with the aeration pad. In yet another embodiment, stitches of thread may attach the gasket and the aeration fabric pad. A sealant material may also be provided at the generally continuous interface to seal any voids between the gasket and the aeration pad.
Technical advantages of the present invention include an aerator pad assembly which reduces or eliminates leak paths between components of a railway hopper car. Another technical advantage includes increasing the strength of the aeration pad by placing the reinforcing supports thereon. Yet another technical advantage includes the increased length of the generally continuous interface provided by the perimeter of the aeration pad, which facilitates a stronger bond between the fabric or material used to form the aeration pad and the associated gasket. Still another technical advantage includes the various sizes and configurations of aerator pad assemblies available within the teachings of the present invention, allowing a wide variety of uses, for example pneumatic and filtration systems.